Introduction to the principle，classification and application of the dispensing valve

Introduction to the principle, classification and application of the dispensing valve

Principle of dispensing valve

The compressed air is sent to the plastic bottle (syringe), and the glue is pressed into the feeding tube connected to the piston chamber. When the piston is in the upper stroke, the piston chamber is filled with glue, and when the piston pushes the dispensing needle downward, the glue is from the needle. The mouth is pressed out. The amount of glue that is dripped is determined by the distance under the piston and can be adjusted manually or in software.

The composition and function of the dispensing valve

The dispensing valve is formed by connecting the cylinder, the valve body and the discharge body up and down. The cylinder and the valve body are separated by a diaphragm to prevent the glue from intruding into the air chamber. The valve in the glue body is fixed on the piston rod, and the valve is used to reach the glue. Turning on and off.

Dispensing valves are generally divided into pneumatic and electric:

Pneumatic dispensing valve:

The dispensing valve is formed by connecting the cylinder, the valve body and the cylinder in three parts. The cylinder and the valve body are separated by an advanced sealing material to prevent glue from entering the cylinder. The cylinder and the cylinder are connected to the valve body of the dispensing valve to ensure concentricity with the cylinder. The pneumatic cylinder is moved by the solenoid valve to drive the center rod up and down, and the up and down movement of the center rod is used to achieve the opening and closing of the glue. According to the way of opening and closing, it is divided into: plunger type dispensing valve, thimble type dispensing valve, lift type dispensing valve, spray dispensing valve, jet dispensing valve; different switching modes, applicable fluids are also Differently, the suckback type dispensing valve adopts the upward movement and the rubber sealing structure, so that the glue is stopped and the glue is broken back at the same time, and the residual glue on the remaining needle is reduced, so that the dispensing does not cause leakage, drawing and the like. The valve body is anodized by aluminum alloy, the sealing material is made of the latest PTFE material, and the contact colloid part is corrosion-resistant material.

Electric dispensing valve:

It includes the pump body and the drive part, and it is easy to install with the stator. Adopting fixed rotor structure design, the sealing performance is good. The rotor and stator pair form a self-sealing structure that is easy to replace. The medium conveying function is realized by the directional rotation of the rotor in the stator cavity. The conveying process does not have any effect on the performance of the media. At the same time, the motor can be easily reversed by the motor reversal to ensure the cleanness of the media and materials without dripping and pollution.

Special introduction to ceramic dispensing valve

The ceramic dispensing valve uses high-tech new ceramic structural materials to make the sealing parts and wearing parts of the valve. The ceramic material is chemically stable and extremely hard (Rockwell hardness HRC90), second only to diamond. Therefore, the valve has extremely high wear and corrosion resistance.

The ceramic dispensing valve can greatly improve the smoothness and sealing of the industrial piping system, and can minimize the leakage to protect the environment.

The use of ceramic dispensing valve can greatly reduce the number of maintenance and replacement of the valve, improve the safety and stability of the supporting equipment operating system, and save equipment repair costs.

The raw materials for manufacturing ceramics are wide and the cost is low. Aluminum, zirconium, silicon and the like can be used to produce ceramic materials with superior performance, which can save a lot of metal materials and rare mineral resources.

Here are seven common dispensing valves on the market.

Spray valve

Spray valves are best suited for low viscosity fluids, especially those with a viscosity of less than 1000 cps. The viscosity of water is 1 cps, and the viscosity of mustard is about 200,000 cps. To choose a suitable spray valve, consider the injection angle of the valve itself and the control module. The control module ensures that the fluid is atomized before it is ejected, and after the injection, it can be quickly restored to its original state, thus preventing fluid from clogging within the valve. Spray valves are often used in three paint-coating fluid types.

Needle valve

Due to its high operability for liquids, the needle valve is suitable for a wide range of single-component fluids and is used in micro-adhesive applications. These valves are generally adjustable to operate high viscosity non-filled fluids at high pressures. Needle valves operate at varying lengths and are therefore suitable for sizing applications for low to medium viscosity fluids. The needle valve has a valve needle that is mounted between the wet chamber and the moving parts. The valve needle can be replaced, so that an inspection plan can be made according to the number of movements of the needle valve. Needle valves are not suitable for use with abrasive fluids to prevent blockage of the passage inside the valve.

Diaphragm valve

Diaphragm valves are used in adjustable, high frequency sizing applications for many low to medium viscosity fluids such as glues, solvents and abrasive materials. The diaphragm valve is lightweight and easy to maintain.

Short tube valve

The short tube valve is suitable for high viscosity paste, syrup and gel fluids. In order to be able to deliver high viscosity fluids, the spool valve must be operated at high pressure. This type of valve has a suction function.

Short tube valves are also suitable for scribing applications. Under certain automatic controls, the spool valve can be dispensed along the seal track.

Introduction to the principle, classification and application of the dispensing valve

Poppet valve

Poppet valves are similar to short pipe valves, such as the suction function. However, the poppet valve is suitable for low to medium viscosity fluids, and the amount of glue can be controlled less than the short tube valve.

Pinch valve

With a disposable wetted part, the pinch valve is ideal for solvent-borne aggressive fluids. Under pinch control, the valve is capable of medium-accuracy, repeatable sizing operations. Pinch valves are commonly used for sizing applications for two-component mixed fluids and flash dry materials. The pinch tube must be replaced within the specified time limit, but its replacement cost is low.

Volume valve

The volume valve is used for high precision micro-sizing operations. The volume valve is divided into two types: a gas control valve and an electric control valve. The electric control valve is also called a spiral valve. One of these two types is selected depending on the viscosity of the fluid and the amount of glue dispensed. Pneumatic valves operate with lower viscosity fluids than spiral valves. At the same time, the price of pneumatic valves is also relatively low.

The above is the introduction of knowledge about how to choose the dispensing valve. The ceramic dispensing valve can perfectly solve the problem of leakage of the valve. Ceramic dispensing valves produce the least back pressure and the smoothest liquid flow, which is favored by the market.